0x11. C - printf

Description:

The printf function sends formatted output to stdout. A custom _printf() for learning purposes was developed by cohort 19 students Ousama and Fatima. _printf() function format string is a character string, beginning and ending in its initial shift state, if any. These arguments are placed using the percentage '%' operator.

Resources

Secrets of printf by Don Colton

Authorized functions and macros

• write (man 2 write)
• malloc (man 3 malloc)
• free (man 3 free)
• va_start (man 3 va_start)
• va_end (man 3 va_end)
• va_copy (man 3 va_copy)
• va_arg (man 3 va_arg)

Compilation:alembic:

The code must be compiled this way:

*$ gcc -Wall -Werror -Wextra -pedantic .c

As a consequence, be careful not to push any C file containing a main function in the root directory of your project (you could have a test folder containing all your test files, including main functions).

The main files will include your main header file (main.h): #include main.h

Use & Examples

Prototype: int _printf(const char *format, ...); Use - General: _printf("format string", var1, var2, ...);

Examples:

• Basic String: _printf("%s Alx", "Hello");

  • Output: Hello Alx

• Print integers: _printf("This is an array element: arr[%d]:%c", 32, arr[32]);

  • Output: This is an array element arr[32]:A

Many other specifiers and flags were added, and by combining those, the _printf() function generates different output. The following list includes the specifiers and flags allowed.

Use & Examples

Specifiers

Specifier	Output	Examples
c	Character	y
d or i	Signed integer	1024, -1024
s	String of characters	Hello Alx
b	Binary Representation of unsigned integer	01010110
u	Unsigned integer	1024
o	Unsigned octal	432
x	Unsigned hexadecimal integer	3ca
X	Unsigned hexadecimal integer (uppercase)	3CA
S	String with hex-ascii value replacing special chars	\x0A\x0A
p	Pointer address	0x403212
r	Reversed string of characters	dlroW olleH
R	ROT13 Translation of string	Uryyb

Flags

Flag	Description
-	Left-justify the output within the field width that was given; Right justification is the default (see width sub-specifier).
+	Precedes the result with a plus or minus sign (+ or -) even for positive numbers. By default, only negative numbers are preceded with a - sign.
(space)	If no sign is going to be written, a blank space is inserted before the value.
#	Used with o, x, or X specifiers, the value is preceded with 0, 0x, or 0X respectively for values different than zero.
0	Left-pads the number with zeroes (0) instead of spaces when padding is specified (see width sub-specifier).

Width

Width	Description
(number)	Minimum number of characters to be printed. If the value to be printed is shorter than this number, the result is padded with blank spaces. The value is not truncated even if the result is larger.
*	The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

Precision

Precision

Description

.(number)

For integer specifiers (d, i, o, u, x, X): precision specifies the minimum number of digits to be written. If the value to be written is shorter than this number, the result is padded with leading zeros. The value is not truncated even if the result is longer. A precision of 0 means that no character is written for the value 0. For s: this is the maximum number of characters to be printed. By default, all characters are printed until the ending null character is encountered. If the period is specified without an explicit value for precision, 0 is assumed.

Length modifiers

Modifier/Specifier	d & i	u, o, x, X	c	s	p
none	int	unsigned int	int	char pointer	void pointer
h	short int	unsigned short int
l	long int	unsigned long int

Files contained in this repository

Name	Information	Relevant Files
main.h	Header file with the data type struct, standard libraries and custom prototypes.	*.c compilation
_printf.c	Main printf function file. Calls other functions.	_printf.c
_put.c	Custom putchar function.	_put.c
convert_number.c	Functions for number conversion.	convert_number.c
main.c	Main testing file.	main.c
number.c	Functions for handling number specifiers.	number.c
params.c	Functions for handling parameter specifiers.	params.c
print_functions.c	Functions for printing various data types.	print_functions.c
print_number.c	Functions for printing numbers.	print_number.c
simple_printers.c	Simple printing functions.	simple_printers.c
specifier.c	Functions for handling specifiers.	specifier.c
string_fields.c	Functions for handling string specifiers.	string_fields.c

Tasks required for this project

0. I'm not going anywhere. You can print that wherever you want to. I'm here and I'm a Spur for life1. I'm not going anywhere. You can print that wherever you want to. I'm here and I am a Spur for life. Write a function that produces output according to a format. Handle the following conversion specifiers:

• c
• s
• %

1. Education is when you read the fine print. Experience is what you get if you don't Handle the following conversion specifiers:

• d
• i

2. Just because it's in print doesn't mean it's the gospel Handle the following custom conversion specifiers:

• b: the unsigned int argument is converted to binary

3. What one has not experienced, one will never understand in print Handle the following conversion specifiers:

• u
• o
• x
• X

4. Nothing in fine print is ever good news Use a local buffer of 1024 chars to call write as little as possible.

5. My weakness is wearing too much leopard print Handle the following custom conversion specifier:

• S : prints the string. Non-printable characters (0 < ASCII value < 32 or >= 127) are printed this way: \x, followed by the ASCII code value in hexadecimal (uppercase - always 2 characters).

6. How is the world ruled and led to war? Diplomats lie to journalists and believe these lies when they see them in print Handle the following conversion specifier: p.

7. The big print gives and the small print takes away Handle the following flag characters for non-custom conversion specifiers:

• `+´
• space
• `#´

8. Sarcasm is lost in print Handle the following length modifiers for non-custom conversion specifiers:

• l
• h Conversion specifiers to handle: d, i, u, o, x, X

9. Print some money and give it to us for the rainforests Handle the field width for non-custom conversion specifiers.

10. The negative is the equivalent of the composer's score, and the print the performance Handle the precision for non-custom conversion specifiers.

11. It's depressing when you're still around and your albums are out of print Handle the 0 flag character for non-custom conversion specifiers.

12. Every time that I wanted to give up, if I saw an interesting textile, print whatever, suddenly I would see a collection Handle the - flag character for non-custom conversion specifiers.

13. Print is the sharpest and the strongest weapon of our party Handle the following custom conversion specifier:

• r : prints the reversed string

14. The flood of print has turned reading into a process of gulping rather than savoring Handle the following custom conversion specifier:

• R: prints the rot13'ed string

15. All the above options work well together.

Disclaimer

If you happen to use this repo, we scored 184.29%

Authors ©

• @fatimaelasri01
• @OusamaTheCoder